1. Field of the Disclosure
Embodiments disclosed herein relate generally to marine riser buoyancy modules. In particular, embodiments disclosed herein relate to a riser buoyancy module system providing buoyancy to a riser and platform while providing a conduit for a number of intelligent downhole services.
2. Background Art
Offshore oil and natural gas drilling and production, particularly in deep water, relies on substantially vertical conduits called “marine risers” to convey fluids and slurries between the seabed and the surface, including but not limited to, drilling risers, production risers, export risers, steel catenary risers (“SCRs”), and flexible composite flowlines.
Some marine risers, such as SCRs, may include a single conduit, while other risers, such as drilling risers, may include a larger diameter main conduit with a plurality of attached, smaller diameter auxiliary lines, including but not limited to, choke and kill lines, “boost” lines, and hydraulic supply and control lines. In some cases, electrical or fiber optic control umbilicals may also be attached to the main conduit of the marine riser.
Typically a marine riser may be at least partially supported by floatation of one form or another, including for example evacuated buoyancy “cans” or buoyancy modules made from, for example, syntactic foam material. Buoyancy modules may be arranged circumferentially around the main conduit of a marine riser. Marine drilling risers, for example, typically have syntactic foam buoyancy modules, each including two “clamshell” longitudinal half-cylinder buoyancy elements that are clamped around the main conduit, and which have molded-in grooves, recesses and holes to accommodate attachment hardware and auxiliary lines.
To compensate for stress and fatigue along a length of the riser, a wall thickness of the riser in certain areas is often increased to strengthen the riser, causing it to be heavier and more expensive. In addition, a riser monitoring system (“RMS”) may be installed onto the riser to monitor stress points along a length thereof. These installations are typically separate umbilicals laid on the seafloor from an existing subsea umbilical termination assembly (“SUTA”) and require additional SUTAs and flying leads to run over and attach to the riser monitoring sensors. The flying leads are often equipped with floatation devices and secured to the riser to prevent the flying leads from being crushed on the sea floor. However, this system may be prone to snagging a line on a subsea object, thus rendering the system inoperable. In addition, these additional systems that connect to the riser monitoring systems increase the clutter on the sea floor. Further, the riser monitor sensors are permanently installed items, and thus, often are unable to be serviced. Still further, acoustic Doppler current profile (“ADCP”) systems may be required to record current along a length of the riser. ADCP systems may require free standing buoys connected by expensive electrical umbilicals along with additional umbilicals, terminations, sleds and flying leads, which lie along the sea floor taking up valuable real estate and costing top dollar for the installation of the systems.
Accordingly, there exists a need for a riser system capable of combining and securing a number of monitoring systems while providing a base line of buoyancy to the entire riser and platform.